The present invention relates to programmable thermostats, especially where remote and wireless temperature sensors sense a temperature to be wirelessly transmitted to a programmable thermostat.
The prior art describes many programmable thermostats. Many of the advances in making microcomputers smaller and less expensive have shown up in programmable thermostats. For a relatively small price, a programmable thermostat may operate several pieces of HVAC equipment, such as air flow fans, heat pumps and the fans associated with their heat transfer surfaces, air conditioning compressors and the fans associated with their refrigerant coils, and heaters and the fans associated with their heat transfer surfaces. Programmable thermostats have also been adapted to receive inputs of temperature, humidity, gas concentrations, light detection, motion detection, and several other indicators of a room's condition.
The location of environmental sensors have been expanded by moving them into wireless sensor devices. The wireless sensor devices comprise an environmental sensor and a wireless transmitter, along with logic means where the sensor input is stored for wireless transmission to a programmable thermostat. In one example, prior art devices comprise a system where a thermistor senses a temperature, the thermistor response is stored in a microcomputer register as digital data, whereupon the digital data is manipulated to indicate a temperature value. The digital temperature value is converted to an analog wave form which is wirelessly transmitted to a receiver effectively connected with a programmable thermostat. The reception of the analog temperature value is converted to a digital temperature value and stored and/or acted upon by the programmable thermostat. This system further comprises a wireless sensor that can be placed outdoors to sense an outside temperature or can be placed in other remote locations where a wired connection would be inconvenient or too expensive. A battery powered wireless sensor is used in those locations. When using a battery powered wireless transmitter, special care must be made in the overall design to minimize power consumption so the device may operate for a long time without battery replacement.
There is a need for a system where temperature sensing means such as a thermistor can more directly and wirelessly transmit a temperature signal to a programmable thermostat without intervening digital storage.